Yes and No
I see where you're coming from and there's certainly truth to the "conflicting economic interests" argument. But, if Microsoft were to set up a Windows app store and give all of the software makers a 70% take on the revenue (which is what Apple does for its iPhone App Store) and provide a streamlined experience for users to browse and buy software, I think it could be a major success.
It would be opt-in, of course, but if users took to it and started using it as the primary way to discover software, then the software vendors would all be lining up to get on board.